> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-fix-nav-issues.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> System table containing a list of dictionary layouts supported by the server along with their embedded documentation.

# system.dictionary_layouts

<h2 id="description">
  Description
</h2>

Contains the list of dictionary layouts supported by the server, along with embedded documentation for each layout. A dictionary layout determines how a dictionary is stored in memory (or on disk) and how it is looked up; it is specified in the `LAYOUT` clause of a `CREATE DICTIONARY` query.

<h2 id="columns">
  Columns
</h2>

* `name` ([String](/reference/data-types/index)) — The name of the dictionary layout, as specified in the LAYOUT clause.
* `is_complex` ([UInt8](/reference/data-types/index)) — Whether the layout requires a complex key (a key consisting of several attributes or of a non-integer type).
* `description` ([String](/reference/data-types/index)) — A high-level description of what the dictionary layout does.
* `syntax` ([String](/reference/data-types/index)) — How the layout is specified in the LAYOUT clause of a CREATE DICTIONARY query.
* `examples` ([String](/reference/data-types/index)) — Usage examples.
* `introduced_in` ([String](/reference/data-types/index)) — The ClickHouse version in which the layout was first introduced, in the form major.minor.
* `related` ([Array(String)](/reference/data-types/index)) — The names of related dictionary layouts.

<h2 id="example">
  Example
</h2>

```sql title="Query" theme={null}
SELECT name, is_complex, syntax
FROM system.dictionary_layouts
WHERE name IN ('flat', 'hashed', 'complex_key_hashed')
ORDER BY name
```

```text title="Response" theme={null}
┌─name───────────────┬─is_complex─┬─syntax───────────────────────────────────────────────────┐
│ complex_key_hashed │          1 │ LAYOUT(COMPLEX_KEY_HASHED())                             │
│ flat               │          0 │ LAYOUT(FLAT([INITIAL_ARRAY_SIZE n] [MAX_ARRAY_SIZE n]))  │
│ hashed             │          0 │ LAYOUT(HASHED())                                         │
└────────────────────┴────────────┴──────────────────────────────────────────────────────────┘
```

<h2 id="see-also">
  See also
</h2>

* [Dictionary layouts](/reference/statements/create/dictionary/layouts/overview) — Information about dictionaries and their layouts.